Update 数组相关.md

blogs/Algorithm/剑指 Offer/数组相关.md

@@ -232,3 +232,56 @@ class Solution {
 }
 ```
 
+[56 - II. 数组中数字出现的次数 II](https://leetcode-cn.com/problems/shu-zu-zhong-shu-zi-chu-xian-de-ci-shu-ii-lcof/)
+
+```java
+class Solution {
+    public int singleNumber(int[] nums) {
+        Arrays.sort(nums);
+        for (int i = 0; i < nums.length - 2; i += 3) {
+            if (nums[i] != nums[i + 2]) {
+                return nums[i];
+            }
+        }
+        return nums[nums.length - 1];
+    }
+}
+```
+
+```java
+class Solution {
+    public int singleNumber(int[] nums) {
+        Map<Integer, Integer> map = new HashMap<>();
+        for (int i : nums) {
+            int count = map.getOrDefault(i, 0);
+            map.put(i, count + 1);
+        }
+        for (Integer i : map.keySet()) {
+            if (map.get(i) == 1) {
+                return i;
+            }
+        }
+        return -1;
+    }
+}
+```
+
+```java
+class Solution {
+    public int singleNumber(int[] nums) {
+        int[] count = new int[32];
+        for (int i : nums) {
+            for (int j = 0; j < 32; j++) {
+                count[j] += i & 1;
+                i = i >>> 1;
+            }
+        }
+        int res = 0, flag = 3;
+        for (int i = 0; i < 32; i++) {
+            res += (1 << i) * (count[i] % flag);
+        }
+        return res;
+    }
+}
+```
+